The Kensington Palace official Twitter account posted a teaser overnight (er, early in the morning for those of you across the pond!) teasing a "very special photo" that will be released later on Saturday.

The royal Twitter read:

We'll be posting a very special photo of Prince George & his little sister Princess Charlotte late tonight. Can't wait to share it with you!
— Kensington Palace (@KensingtonRoyal) June 6, 2015